*puts on glove, grabs into lab coat, shuffles, shuffles... pulls out a crumpled piece of paper and spreads it onto the table*
There we go.
Guide to Match-Up Ratios by Praxis
50:50
Very even matchup. Definition should be fairly obvious.
55:45
No character has a true solid advantage, but one has seemingly better/easier tools, or one character profits more from winning a rock/paper/scissors guessing game.
60:40
One character has clearly better tools in the matchup. However, the other character does have responses him, and the matchup is still winnable through outplaying the opponent or outspacing his tools and countering with the weaker ones well placed.
65:35
One character has options that shut down the other's options. Counterpicking should be considered, but it's not completely unwinnable, but rather simply requires one player to far outplay the other.
70:30
Something about the character in the advantage completely shuts down the other character. Counterpicking is heavily recommended - or rely on them not knowing the matchup and you knowing it incredibly well.
Anything past 70:30
Pretty much unwinnable matchups like Dedede vs Donkey Kong.
Ah yes. That should help you guys. Taken from my amazing Fox Matchup Index. <3
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To contribute to the topic at hand:
I think that Wolf, among several other characters in Mid Tier, has a lot of potential.
True, Dedede, Wario, Pikachu... all those characters do very well against him. However, if you look at the metagame evolution, you will see that all those characters had more or less recent evolution.
Prime example for the opposite is Meta Knight. His metagame has reached a point of stagnation. Remember back in the day when SBR Tierlist 1 was released, where everyone agreed that Meta Knight would have absolutely no disadvantageous matchup? Where so many tournaments were won by Meta Knight only, especially Mew2King?
Well, look at that. A lot of characters have caught up by now - especially Snake, Diddy, Falco and the Ice Climbers. Meta Knight already was at his peak in the Tierlist 2-"era" about 9 months ago. His metagame declined. Players like Ally, ADHD, SK92, lain, etc., have discovered ways to beat Meta Knight's Top Players. He still has no disadvantageous matchups (yet), but he has even ones. That's metagame advancement.
This has happened to only High Tier characters, so far, with the exception of Sheik who has gotten a HUGE boost lately. Slowly, the other Mid Tier characters are following, though. However, Wolf is one of the characters who has hardly had any advancement so far. Sure, the lack of Top Level-players like Ally is one of the reasons why Wolf is severely underplayed.
However, one of the most important reasons is that he's destroyed by Dedede's CGs. Look at the characters who are suffering from that - Mario, Luigi, Donkey Kong, Wolf, Bowser, Samus... All those characters have hardly players on top or very high level, if they have one at all.
I think that "lol i pick D3 & CG u. GGs" is a huge turn-off. Add this to a high learning curve (true for all those characters) and the general laziness of the Brawl community, and you have a group of Mid Tier characters noone wants to play as.
tl;dr-version: I think Wolf can become viable in the future, if his metagame is able to evolve. For now he isn't.